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Some Like it Hotter

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Temperature significantly influences a certain bacterium’s ability to block mosquitoes from transmitting malaria, according to postdoctoral scholar Courtney Murdock and colleagues in the Center for Infectious Disease Dynamics and the Department of Entomology. Researchers found that at warmer temperatures (82°F), bacteria in the genus Wolbachia reduced the proportion of mosquitoes infected with malaria parasites as well as the parasite burden, or number of malaria parasites within each mosquito. At lower temperatures (68°F), Wolbachia had no effect on the proportion of infected mosquitoes or parasite burden.

Murdock explained that Wolbachia naturally infects about 65 percent of insects. Infected insects can exhibit desirable disease-control characteristics.

"Wolbachia represents a promising new tool for controlling malaria due to its demonstrated ability to block the development of the malaria pathogen within mosquitoes," Murdock said. "However, much of the work on the Wolbachia-malaria interaction has been under highly simplified laboratory conditions. We investigated the ability of Wolbachia to block the transmission of mouse malaria parasites across variable environmental conditions more reflective of conditions in the field."

She noted that the team's findings demonstrate that temperature also could potentially enhance malaria transmission in certain environmental contexts.

"These results suggest that developing this technology requires an improved understanding of how mosquitoes, Wolbachia, and malaria parasites interact in diverse transmission settings," she said.

The results of the team’s study—funded by the National Science Foundation, National Institutes of Health, and Pennsylvania Department of Health—appeared in the February 3 issue of Nature Scientific Reports.

The researchers plan to duplicate their experiment using a species of malaria parasite that affects humans to determine whether the temperature effects they observed in the mouse model also will be observed in a human system.

"Because mosquitoes, malaria parasites, and humans do not interact in perfect, constant temperature environments," Murdock said, "our next step is to explore how additional environmental variation — such as daily temperature fluctuation and differential access to food resources in the mosquito larval and adult environments — affects the transmission-blocking ability of Wolbachia."


Sara LaJeunesse